The present invention relates a method for controlling the supply of fuel and ignition sparks to a combustion engine and, in particular, to a method for cutting off the supply of fuel upon deceleration of the combustion engine and retarding and then gradually advancing the timing of ignition spark after resuming the supply of fuel.
It is a well known practice in an engine system for automotive vehicles such as disclosed in the U.S. Pat. No. 3,969,614 that, while an internal combustion engine in which air-fuel mixture is ignited by an ignition spark is under deceleration, the supply of fuel to the engine is cut off to decrease an engine output torque. This is also effective to enhance fuel economy. The supply of fuel is, of course, resumed to increase the engine output torque, when the engine is accelerated from the decelerating condition. It is experienced very often that this abrupt increase in the engine output torque deteriorates a vehicle driveability. A more gradual increase in the engine output torque is desired at a transition from cutting off to resuming the supply of fuel to the engine.